(1) Field of the Invention
This invention relates to a semicircular packing sealing the semicircular hole pierced in a cam fitting portion when setting the cylinder head of an overhead cam-type automobile internal combustion engine.
(2) Description of the Prior Art
The existent semicircular packing is semidiscoidal and made of an elastic member such as rubber and plastic or of a metallic member. However, there have been disadvantages in those respective members as follows: the semicircular packing made of the elastic member has been formed larger than the pierced hole from the requirement of interference, so that there has been a likelihood that a gap will be between the cylinder head and the cylinder head cover gasket at the outward extend of the auricular, i.e. ear-like portion of the semicircular packing (at both ends of edge portion of the semicircular packing). And, to get rid of this gap, it has been necessary to apply sealing material or increase load to the cylinder head cover gasket, which has been troublesome, taking much time.
And, in the case of forming the semicircular packing to be approximately equal to the pierced hole or forming with material softer than the semicircular packing, there has been a likelihood that a gap will be caused by the semicircular packing being sunken below the sealed surface of the cylinder head because of increasing load to the cylinder head cover gasket or, even if the load is not heavy, of causing permanent deformation of the elastic member due to aging from many years of use.
And, in the method which involves increasing the load to the cylinder head cover gasket, there has been caused excessive deformation, thereby accelating aging.
On the other hand, when the semicircular packing made of a metallic member has been formed smaller than the pierced hole and coated with sealing liquid to the fill gap between the semicircular packing and the pierced hole, the sealing effect of the sealing liquid has been rapidly decreased in proportion to the increase of the gap and, in the case of a large gap due to dispersion of the size of the semicircular packing, the sealing has been liable to be imperfect. And, when setting again after removing the cylinder head cover gasket, it has been necessary to remove the sealed material thoroughly and to coat it with sealing liquid again which has been trouble, taking much time.